Method and apparatus for spray painting small articles



July 12, 1960 H. E. WILSON, JR

METHOD AND APPARATUS FOR SPRAY PAINTING SMALL ARTICLES Filed July 17, 1956 INVENTOR Harold E. Wilson,Jr. BY 2 ATTORNEY accom any n d1=awings,in which: a

METHOD AND APPARATUS FOR SPRAY PAINTING SMALL ARTICLES Harold E. Wilson, In, Middle River, Md., assignor to The Company, a corporation of Maryland Filed July 17, 1956, Ser. No. 598,273 4 Claims, erils-40s) J The present invention relates to the spray coating of small articles. with paint and'like materials and more particularly. to an improved methodand apparatus for spray paintinga large. pluralitylof small articles atone time. 1

The handling of small articles for painting presents substantial practical problems in connection with the manufacture of such parts. Thus, in orderto assure that all surfaces of the article are properly covered, it is necessary to provide for the relative movement. of the parts and the spray applicator so that the spray is directed towarclall surfaces of the parts. Where the volume of manufacture of the parts is such as not to warrant elaboratehandling apparatus, it has. been common practice to hang or hand-hold the parts during the spraying operation. As will be readily apparent this involves considerice tainer incorporated in the apparatus of Fig. 1, illustrating the spray painting method of the invention;-

Fig. 3 is a transverse cross-sectional view taken along line 3-3 of Fig. 2; and

Fig. 4 is a transverse cross-sectional view taken along line 4--4 of Fig. 2. J

Referring now to the drawing, the numeral 10 designates a base memben'uponwhich are mounted longitu-.

dinally spaced supports 11, 12. The supports 11, 12 are provided'with semicircular recesses 13, 14, respectively, which are aligned along a common axis and have" suitable anti-friction bearing means (not shown) therein.

Carried by the :supports 11,- 12 and journaled for rotation by the anti-friction bearing means therein, isza cylindrical container 15. The container is open at one end and has a wall 16 substantially closing its other end. The end wall 16, in accordance with the invention, has

a relatively small aperture 17 located in concentric relation with the cylindrical side wall of the container.

At spaced points between its ends, the container 15 has are received within the semi-circular recesses 13, 14 in supports 11, 12 and engaged with the anti-friction bearof the final cost.

.Accordingly, the present invention providesjnew and improved arrangements for the handling of small parts so that a large plurality thereof may be spray painted at one time, without undivided handling of th'eparts and with improved efficiency in the utilization of the paint. More specifically, the invention provides an improved method and apparatus for spray painting a largeplurality of small articles wherein the articles are placedin a rev'olvable container and caused to tumble therein in a random manner. {A spray of paint is directed through the container, from one end to the other thereof, so that all surfaces of all parts are exposed to the sprayand are evenly-coated in a minimum oftime. In accordance with the invention, the container has a small aperture at one end, through which the spray gun orapplicator may be projected, and a removable screen cap is provided at the other end of the container to permit the spray of paint to pass freely out of the container, to be exhausted. The

removable screen cap normally retains the parts within the container, but may bereadily detached from the container for removal of painted parts or placing of new parts in the container. V J As an ancillary but important feature, the invention .provides a-new and improved apparatus, for spray'paint ing a large plurality ofsmall articles which 'isjcompact,

Fig. 1 is a perspective view of aispray painting appara} itus constructedin accordancewith'the teachings of the invention; .1

Fig. 2 is a longitudinalsection view of thepartsconings therein. The rings 18, 19 and bearing provide for the free rotation of the cylindrical container 15 on the supports 11, 12, as will be readily understood.

To retain the container 15 on the supports 11, 12, one or both thereof may be provided with means extending over the upper part of the container to restrain the latter against upward movement. In the illustrated apparatus the support 12, toward the backof the container15, i s;

provided with a retaining member'ZO hinged at one side to thesupport 12 and releasably engaging the support 12 at the other side.- In the perspective view of Fig. 1, a suitable hinge (not visible) connects the retainer 20-to' the support 12 at the right-hand side of theapparatus, as viewed from the back. At the other side, the support 12 has guides 21, which project upwardly and engage the opposite surfaces of the retainer 20 to properly align it with the support. Also mounted on the support '12 is a pivoted locking member 22 which engages with a projection 23 on the retainer 20 to hold the latter down, in its assembled position.

In accordance with the invention, the container 15 is provided interiorly with an evenly spaced plurality of longitudinally extending bafiies 24. In the illustrated apparatus, the bailies' 24 are straight, generally triangular in cross section, and have flanges 24' at the base enabling the bafiles to be conveniently secured to the inner walls of the container 15, as by welding, for example. The baffles 24 extend throughout substantially the whole of the length of the container '15, and if desired, instead of being straight as shown in Fig. 2, may be curved baffles, and placed in a generally helical arrangement about the in terior of container 15. In the apparatus illustrated herein, three baflies 24 are provided, but it is to be understood that a larger or smaller number may be used.

At its forward or open end, thecontamer 15 has a lipor i bead 25 forming a small outward projection. Received over'the open end of the container 15 andremovably locked in place by the bead 25 isa cap" comprising a thin annular frame 27 and circular screen 28. The; annular frame 27 has minimum radial dimensions, sufiicient merely to impart adequate strength to theica'p 26 and to provide a surface for mounting the screen 28 by its periph eral edge portions. The frame also has a'plurality of axially projecting springlike retaining tabs"29which are received over the annular bead25 at the front end ofthe container 15 serve to releasably retain the cap26rin a closed qs n at t mnt hej n r- .Asjis vtl a in Fig.- 2, the retaining tabs 29 have recessed portions "for Patented July 12, 1960- receiving the bead 25 and lip portions which press resiliently inward against the side wall of the container 15 to effect a resilient engagement of the tabs 29 with the bead 25.

' Adjacent its closed end, the container 15 is provided with a circular band'ist) which is exposed at the back side of the rear support 12. The band 30 is adapted to be engaged with a driving wheel 31, having a surface of friction material, such as rubber. The driving wheel 31 is supported for rotation on the base 10, and, in accordance with the invention, is driven by an air motor 32 that is supplied through an air line 33 with compressed air from a suitable source thereof, not shown. The use of the air motor 32 is particularly advantageous in its present application, since the possibility of causing an explosion of the paint-airv mixture is wholly obviated, and no additional equipment is required in connection with the compressed air source and lines inasmuch as the spraying of the paint is conventionally carried out with compressed air. If desired, however, the container may be belt driven or gear driven, and an enclosed electric motor employed as the driving force.

To effect the spraying of a large plurality of small articles using the new method and apparatus, the screen cap 26is removed from the front end of the container 15, and a large number of unpainted articles 34 are inserted into the container from its open end. These articles for example may be support clips or electrical clips to be painted, or shims to receive zinc chromate primer. The screen cap 26 is then replaced, being thereby locked in place by the plurality of tabs 29.

After the unpainted parts 34 are placed in the container 15 and confined therein by the screen cap 26, the air motor 32 is energized to drive the wheel 31 and effect the rotat ion of the container 15 on its supports 11, 12. The motor 32 is arranged to drive the container at a speed such that the parts 34 will not be held against-the interior walls of the container by centrifugal force, but will be carried up wardly by the baffles 24 and then caused to drop to the bottom of the container by gravity. This effects a thor ough tumbling of the parts 34, so that the parts are kept in random motion. 7

When the container is rotating in the manner desired, a paint spray gun 35, which in itself may be of conventional design, is held up to or secured near the aperture 17 in the rear wall 16 of the container, and a spray of paint is directed into the interior of the container through the aperture 17. In this respect, it will be understood that the aperture 17 is concentric with the walls of the container 15, and therefore with the axis of rotation thereof. Accordingly, the position of the aperture does not change when the container is rotating.

As the spray of atomized point is directed into the interior of the container 15 by the spray gun 35, it falls upon the exposed surfaces of the parts 34 confined within the container. The spray is effective throughout the whole of the length ofthe container 15 since the forward end thereof isopen to the flow of the atomized paint, and the spray moves longitudinally through the container substantially unimpeded, except for the presence of the parts 34. Such of the paint particles as are impinged upon the parts 34 are retained thereon, in the desired manner, while the excess flows freely out of the front end of the container through the screen cap 26, and is exhausted in 2. conventional manner, as by passing through a water screen, for example.

If desired, an automatic spray gun arrangement can be used with the gun arranged to operate cyclically. For instance, the gun can spray for three seconds, shut off for seven seconds, spray for three seconds, shut off for seven seconds, and so on for a total of six or so cycles. The seven second or so drying period of each cycle permits the paint particles on each part 34 to dry somewhat, thereby inhibiting the accumulation of excess paint on the parts and preventing them from sticking together. Preferably,

the drying periods for each cycle are obtained by shutting off by automatic means the flow of paint to the gun, while allowing the high pressure air responsible for spraying the paint to continue to flow throughthe spray gun so as to contribute somewhat to the drying of the parts.

At all times when the container is rotating, the parts 34 are tumbled about at random so that all surfaces thereof are presented to the direct flow of the paint spray. In this manner, all parts are fully covered with the paint in a practical minimum of time.

After the operation has continued for a suflicient length of time to effectively coat all surfaces of the plurality of parts 34, the spray gun 35 is shut off and the air motor 32 de-energized. The rotating container 15 is allowed to come to rest, and the screen cap 26 is then removedto enable the painted parts to be discharged into a suitable container for heating, drying or other further operations. Preferably, the discharge of the painted parts is effected by merely tipping the entire assembly so that the parts fall by gravity out of the open end thereof.

The advantages of the invention should now be apparent. The new method and apparatus provide for high efficiency in the painting of small articles since a large plurality thereof may be painted at the same time without special handling of the parts as has been necessary in the past. Moreover, the invention provides for an eflicient utilization of the paint, because the flow of atomized paint is passed about the randomly moving parts throughout a relatively substantial longitudinal distance. Accordingly, there is a maximum opertunity for the paint particles to fall upon a surface of one of the parts before reaching and passing out through the screen cap 26.

Another advantage of the new apparatus is that it'may be inexpensively manufactured and is capable of use in connection with the painting of a wide variety of parts, so that the apparatus is suitable for economical use in small operations, as well as large.

It should be understood, however, that the specific form of the invention herein illustrated and described is intended to be representative only, as certain changes may be made therein without departing from the teachings herein disclosed. Reference should therefore be made to the following appended claims in determining the full scope of the invention.

I claim:

1. Apparatus for spray coating a large plurality of small articles comprising in combination a container, said container being open at one end so that a flow path can be established therethrough, means to support said con tainer for rotation about a substantially horizontal axis, a wall substantially closing the other end of said container, in which is located a relatively small aperture disposed in concentric relation to the axis of rotation of said container, a screen cap removably secured to said container at the open end thereof, baffle means disposed on the inner walls of said container for agitating said articles while said container is rotating, means for rotating said container, and means located adjacent said aperture for directing a spray of coating material through the interior of said container and toward said screen.

2. The spray coating apparatus of claim 1, further characterized by said means to rotate comprising an air driven motor.

3. Rotating apparatus for the spray coating of a large plurality of small articles comprising a container mounted for rotation about a substantiallyhorizontal axis, one end of said container being substantially closed but having a centrally disposed aperture therein, the other end of said container being open and covered by a screen, spray means disposed adjacent, said aperture and arranged to establish a flow path through said container by directing a spray of coating material through the interior of said container during the rotation thereof, the sprayed material being substantially unimpeded by said screen, with a portion of the spray not intercepted by 4. The device as defined in claim 3 in which said screen is removable for the loading and unloading of articles from said container. I

References Cited in the file of this patent UNITED STATES PATENTS 6 Beckinsale et a1 Dec. 15, 1931 Jorgenson et a1, July 31, 1945 Gcldhof Aug. 1, 1950 Bibby et a1. Oct. 2, 1951 Lowry etal Aug. 19, 1952 Wiklund June 7, 1955 Clay et al. Feb. 28, 1956 Babour L Aug. 7, 1956 Wurster July 16, 1957 

